In the retreading of a buffed tire with precured tread material, the precured tread material is fitted on the tire with a cushion layer of uncured rubber between the buffed area of the tire and the tread material. The proximate ends of a length or lengths of the precured tread material have been, prior to the present invention buffed and coated with a rubber cement. Before the curing step, the two ends are temporarily spliced together by staples.
In practice, the ends of the tread material which are to be sliced together are so dimensioned relative to each other that one end will overlap the other with the overlap about a half an inch in length so that the overlap when forced against the cushion layer of uncured rubber is crammed against the other end not only compressing the uncured rubber strip but also compressing the adjacent end portions of the tread material in a manner such that they are stressed for several inches from the splice to an extent greater than any stress in other portions of the retread material. The butted ends are then held together by staples which are removed after the retreaded tire has been cured by heat and pressure.
It will be appreciated that since flat tread material is being fitted against a curved buffed area, the excess length of tread material to be absorbed lengthwise of the tread material is greater adjacent its side margins than in its central portions. While the practice is to ensure enough of an overlap to avoid gaps under production conditions gaps do occur and these are filled with lengths cut from an uncured rubber strip.
A disadvantage of splices affected in the above described manner is that the lengthwise compression of the tread material adjacent the splice results in the cushion layer being cured at a somewhat lowered pressure than the tread material remote from the splice since the curing pressure is reduced by the tendency of the tread material adjacent the splice to return to its normal length in which it would be humped slightly away from the tire.